4340 vs SAE 4320 Carbon Steel (Annealed at 850 °C (1560°F))
Property comparison of 4340 and SAE 4320 Carbon Steel (Annealed at 850 °C (1560°F)), both carbon steel.
| Property | 4340 | SAE 4320 Carbon Steel (Annealed at 850 °C (1560°F)) | Difference |
|---|---|---|---|
| Yield strength | 470 MPa | 425 MPa | -10% |
| Tensile strength | 745 MPa | 580 MPa | -22% |
| Elongation | 22 % | 29 % | +32% |
| Elastic modulus | 200,000 MPa | 200,000 MPa | 0% |
| Shear modulus | 76,923 MPa | 76,923 MPa | 0% |
| Poisson ratio | 0.3 | 0.3 | 0% |
| Density | 7,850 kg/m³ | 7,850 kg/m³ | 0% |
| Brinell hardness | 217 HB | 163 HB | -25% |
| Thermal conductivity | 51.9 W/m·K | 51.9 W/m·K | 0% |
| Specific heat | 462 J/kg·K | 457 J/kg·K | -1% |
| Coefficient of thermal expansion | 0.000012 1/K | 0.000012 1/K | 0% |
| Melting point | 1,480 °C | 1,480 °C | 0% |
| Reduction in area | 50 % | 58 % | +16% |
Difference is SAE 4320 Carbon Steel (Annealed at 850 °C (1560°F)) relative to 4340. Values are taken from the representative row of each material; both materials may have multiple heat treatments or conditions on their individual pages.
Identification
- grade
- 4340
- standard
- SAE
- heat treatment
- Annealed at 810 °C (1490 °F)
- grade
- 4320
- standard
- SAE
- heat treatment
- Annealed at 850 °C (1560°F)
About AISI/SAE 43xx nickel-chromium-molybdenum steels
43xx grades add nickel to the chromium-molybdenum recipe of 41xx, raising toughness and hardenability. 4340 is the highest-performing grade in this family and is used for landing gear, gun barrels, and heavily loaded shafts.
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